Cindy Hahn was pulled over for a seatbelt violation but says that the incident escalated and she was punched in the face by an officer - while her young children watched from the car.

The video from the incident, which took place in Carlsbad, California, appears to show Ms Hahn being hit in the face by an officer with his closed fist while she's pinned to the ground by him and another cop.

Her children, then aged seven and 11, are looking on as she screams, reports the New York Daily News .

She says she was asked if it was her vehicle, and when she said no, he said: 'mind your own f****** business'."

After the incident, she complained about the treatment on a non-emergency police line, and was subsequently stopped by the policeman further along her journey.

She was pulled over on the pretext that she had committed a 'seatbelt violation', says the brutality complaint.

The document says: "Officer Valentine had Ms Hahn exit the vehicle and began attacking her in front of her children who were in the back seat of the car. While she was being beaten and pummelled, Ms Hahn was crying out for help.

"Shortly thereafter, another Carlsbad patrol vehicle arrived at a high and reckless rate of speed, travelling in reverse.

Courts: The brutality complaint says she was pulled over on the pretext she had committed a 'seatbelt violation' (Photo: YouTube)

It then details how the new attendee, Officer J Knisley, got out of the vehicle and "joined in the attack", allegedly punching Ms Hahn with a closed fist to the face.

She claims in court documents to have suffered memory loss and brain trauma following the alleged incident on July 31, 2013.

The release of the video apparently led to charges of resisting arrest and battery on a police officer against Hahn to be dropped, but the violent confrontation and falsification of police reports still merits a lawsuit, she believes.

Ms Hahn's dad Mike Dalton said he believes the lawsuit is justified.

“There was no need to punch her in the face."

Carlsbad officials said they are looking “forward to bringing this lawsuit before the proper judicial authorities as soon as possible.”

“We are prepared to provide a complete and detailed account of the facts of this incident in a courtroom, not in the media,” a statement provided to local media reports.